Sector translation layer for hard disk drives

ABSTRACT

An apparatus having a memory and a controller is disclosed. The memory may have a write head and sectors in tracks. The controller may have a sector map and a translation map and may be configured to (i) receive a write command having a logical block address and a range value, (ii) examine the sector map to find a sector sequence (a) marked free, (b) about to reach the write head and (c) at least as long as the range value, (iii) write new data in the sector sequence, (iv) update the translation map to associate the logical block address of the write command with a physical address of the written sectors and (v) update the sector map according to the sectors written. Each entry in the sector map generally corresponds to a respective sector and indicates whether the respective sector contains valid data or is free.

FIELD OF THE INVENTION

The present invention relates to hard disk drives generally and, moreparticularly, to a method and/or architecture for a sector translationlayer for hard disk drives.

BACKGROUND OF THE INVENTION

Accessing a sector of a conventional rotating media to read or writedata involves delays called a seek time delay and a rotational latencydelay. The seek time delay measures a time for a head assembly on anactuator arm to travel to a track of a disk platter where the data isread or written. The rotational latency is a delay waiting for therotation of the disk platter to bring the requested sector to the headassembly. Both types of delay impact data transfer performance. Theimpact can be significant during random reads and/or writes.

It would be desirable to implement a sector translation layer for harddisk drives.

SUMMARY OF THE INVENTION

The present invention concerns an apparatus having a memory and acontroller. The memory may have a write head and sectors in tracks. Thecontroller may have a sector map and a translation map and may beconfigured to (i) receive a write command having a logical block addressand a range value, (ii) examine the sector map to find a sector sequence(a) marked free, (b) about to reach the write head and (c) at least aslong as the range value, (iii) write new data in the sector sequence,(iv) update the translation map to associate the logical block addressof the write command with a physical address of the written sectors and(v) update the sector map according to the sectors written. Each entryin the sector map generally corresponds to a respective sector andindicates whether the respective sector contains valid data or is free.

The objects, features and advantages of the present invention includeproviding a sector translation layer for hard disk drives that may (i)improve write performance compared with conventional hard disk drives,(ii) incorporate a limited amount of NAND or NOR flash memory formapping purposes, (iii) reduce a seek time to a writable sector, (iv)reduce rotational latency delays, (v) provide a single controller thatworks with both the flash and the rotating media, (vi) write tonon-sequential sectors, (vii) write to multiple platter surfacessimultaneously and/or (viii) be implemented with one or more integratedcircuits.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of the presentinvention will be apparent from the following detailed description andthe appended claims and drawings in which:

FIG. 1 is a block diagram of an apparatus in accordance with a preferredembodiment of the present invention;

FIG. 2 is a detailed block diagram of a storage media and a storagemedia interface circuit;

FIG. 3 is a functional flow diagram of a sector translation layer;

FIG. 4 is a diagram of a portion of a disk platter;

FIG. 5 is a functional flow diagram for mapping logical block addressesto physical addresses;

FIG. 6 is a flow diagram of a write method;

FIG. 7 is a flow diagram of a trim method;

FIG. 8 is a flow diagram of a defragmentation method;

FIG. 9 is a flow diagram of a cache flush method;

FIG. 10 is a flow diagram of a single read method;

FIG. 11 is a flow diagram of a multiple read method;

FIG. 12 is an illustration of head movement based on read sequences withand without rearrangement; and

FIG. 13 is a block diagram of another apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention provide a sector translation layerfor hard disk drives. The architecture generally implements a “tightlycoupled hybrid” solution, meaning a controller that works withnonvolatile memory for mapping purposes and at the same time writes in(on) a rotating media. The writes may be made in sequential and/ornon-sequential sectors. The architecture may improve random writeperformance by reducing head movement prior to the writes. Furthermore,the hard disk drive may utilize multiple heads simultaneously (orconcurrently) to actively write data in (on) multiple platter surfaces.

Referring to FIG. 1, a block diagram of an example implementation of anapparatus 90 in accordance with a preferred embodiment of the presentinvention is shown. The apparatus (or circuit, system, or device) 90generally implements a computer having rotating storage media. Theapparatus 90 generally comprises a block (or circuit) 92 and a block (orcircuit) 100. The circuit 100 generally comprises a block (or circuit)102 and a block (or device) 104. The circuits 92 to 102 may representmodules and/or blocks, embodiments of which include one or more ofhardware circuitry, executable code (e.g., software, microcode,programming instructions, firmware, etc.) in a storage device used bythe hardware circuitry and/or one or more electronic design tools.

One or more signals (e.g., HOST I/O) may be exchanged between thecircuit 92 and the circuit 100. The signal HOST I/O may be abidirectional signal that transfers host input/output information. Thesignal HOST I/O generally includes, but is not limited to, a logicaladdress component and a range value used to access data in the circuit100, a host command component that controls the circuit 100, a writedata component that transfers write data from the circuit 92 to thecircuit 100 and/or a read data component that transfers read data fromthe circuit 100 to the circuit 92. One or more signals (e.g., CONTROL)may be exchanged between the circuit 102 and the device 104. The signalCONTROL may be a bidirectional signal that transfers control informationand feedback information. The signal CONTROL generally includes, but isnot limited to, a physical address component used to access data in thedevice 104, a memory command component that controls the device 104(e.g., read or write commands) and/or one or more feedback components. Adata signal (e.g., DATA) may be exchanged between the circuit 102 andthe device 104. The signal DATA may be a bidirectional signal. Thesignal DATA generally conveys data written to and/or read from thedevice 104. Other signal components may be implemented to meet thecriteria of a particular application.

The circuit 92 may implement a host circuit. The circuit 92 is generallyoperational to read from and write data to the device 104 via thecircuit 102. When reading or writing, the circuit 92 transfers a logicaladdress value and a range value in the signal HOST I/O to identify whichset(s) of data is(are) to be written to or read from the device 104. Theaddress generally resides in a logical address range of the circuit 92.

The circuit 92 may use a logical block addressing scheme to specifylocations of data blocks stored on storage devices, generally secondarystorage systems such as hard disks (e.g., the device 104). The logicalblock addressing scheme is generally a linear addressing scheme. Theblocks may be located by an integer index, with an initial block beingLBA 0, a next block being LBA 1, and so on.

The circuit 100 may implement a hard disk drive circuit. The circuit 100is generally operational to store write data received from the circuit92 via the signal HOST I/O. The circuit 100 may also be operational tosend read data via the signal HOST I/O to the circuit 92. In variousembodiments, the circuit 100 is configured to communicate with thecircuit 92 using one or more communications interfaces and/or protocols.According to various embodiments, one or more communications interfacesand/or protocols may comprise one or more of a serial advancedtechnology attachment (e.g., SATA) interface; a serial attached smallcomputer system interface (e.g., serial SCSI or SAS interface), aperipheral component interconnect express (e.g., PCIe) interface; aFibre Channel interface, an Ethernet Interface (such as 10 GigabitEthernet), a non-standard version of any of the preceding interfaces, acustom interface, and/or any other type of interface used tointerconnect storage and/or communications and/or computing devices.

The circuit 102 may implement a controller circuit. The circuit 102 isgenerally operational to control reading from and writing to the device104 in response to commands and logical addresses received from thecircuit 92 via the signal HOST I/O. Control of the device 104 isgenerally accomplished using components of the signal CONTROL. Data maybe exchanged with the device 104 in the signal DATA.

The device 104 may implement one or more rotating storage media. Thedevice 104 is generally operational to store data in a nonvolatilecondition. The data may be received from and sent to the circuit 102 inthe signal DATA. Control of the storage operation may be implemented bythe signal CONTROL. In various embodiments, the device 104 may implementmagnetic media, optical media and/or magneto-optical media. Other typesof storage media may be implemented to meet the criteria of a particularapplication.

The circuit 102 generally comprises a block (or circuit) 120, a block(or circuit) 122 and a block (or circuit) 124. The circuits 120 to 124may represent modules and/or blocks, embodiments of which include one ormore of hardware circuitry, executable code (e.g., software, microcode,programming instructions, firmware, etc.) in a storage device used bythe hardware circuitry and/or one or more electronic design tools.Additional circuitry may be implemented in the circuit 102 to meet thecriteria of a particular application.

A signal (e.g., MAPS) may be exchanged between the circuit 120 and thecircuit 122. The signal MAPS may be a bidirectional signal thattransfers a multi-layer address translation map and a physical addressfree sector map between the circuit 120 and the circuit 122. A signal(e.g., INT) may be exchanged between the circuit 120 an the circuit 124.The signal INT may be a bidirectional signal that transfers internalcommunications involving data and instructs between the circuit 120 andthe circuit 124 for accessing the device 104.

The circuit 120 may implement a processor circuit. The circuit 120 isgenerally operational to control reading to and writing from the device104. The circuit 120 may include an ability to encode the write datareceived from the circuit 92. The resulting encoded write data may bestored in the device 104. The circuit 120 may also include an ability todecode the read data received from the device 104. The resulting decodeddata may be presented to the circuit 92 via the signal HOST I/O and/orre-encoded and written back into the circuit 120. The circuit 120comprises one or more integrated circuits (or chips or die) implementingthe controller of one or more drives, embedded storage, or othersuitable control applications.

The circuit 122 may implement one or more nonvolatile (or persistentstorage) memory circuits. According to various embodiments, the circuit122 generally comprises one or more nonvolatile semiconductor devices(e.g., solid-state memories). The circuit 122 may be operational tostore data in a nonvolatile condition. The circuit 122 is generallyimplemented as NAND flash memory, NOR flash memory, flash memory usingpolysilicon or silicon nitride charge storage cells, two-dimensional orthree-dimensional nonvolatile memory, ferromagnetic memory, phase-changememory, racetrack memory, resistive random access memory, magneticrandom access memory and similar types of memory devices and/or storagemedia. Other nonvolatile memory technologies may be implemented to meetthe criteria of a particular application.

The circuit 124 may implement a storage media interface (I/F) circuit.The circuit 124 is generally operational to communicate with and controlthe device 104. The circuit 124 may also be operational to communicatewith the circuit 120 via the signal INT. The data is sent to andreceived from the circuit 124 via the signal DATA. A command componentof the signal CONTROL may govern positioning of read/write heads in thedevice 104. A position component of the signal CONTROL may provide aposition of the read/write head to the circuit 124. A speed component ofthe signal CONTROL generally controls a rotational speed of one or moredisk platters of the device 104.

Referring to FIG. 2, a detailed block diagram of an exampleimplementation of the device 104 and the circuit 124 is shown. Thecircuit 124 generally comprises a block (or circuit) 142, a block (orcircuit) 144, a block (or circuit) 146, a block (or circuit) 156 and ablock (or circuit) 158. The device 104 generally comprises a block (orcircuit) 148, a block (or device) 150, a block (or device) 152 and ablock (or device) 154. The circuits 142 to 158 may represent modulesand/or blocks, embodiments of which include one or more of hardwarecircuitry, executable code (e.g., software, microcode, programminginstructions, firmware, etc.) in a storage device used by the hardwarecircuitry and/or one or more electronic design tools.

The signal DATA may be exchanged between the circuit 146 and the circuit148. The signal CONTROL generally comprises a signal (e.g., CMD), asignal (e.g., POS) and a signal (e.g., SPEED). The signal CMD may carrycommand information generated by the circuit 156 that controls thedevice 152. The signal POS may convey position information from thedevice 152 to the circuit 156. The signal SPEED may be a speed controlsignal generated by the circuit 156 that controls a rotational speed ofthe device 154. The signal INT generally comprises a signal (e.g., WRITEDATA) and a signal (e.g., READ DATA). The signal WRITE DATA may bereceived by the circuit 144 from the circuit 120. The signal WRITE DATAgenerally carries write data to be stored in (on) the device 150 throughthe circuit 148. The signal READ DATA may be generated by the circuit144 and transferred to the circuit 120. The signal READ DATA may carrydata read from the device 150 by the circuit 148.

The circuit 142 may implement an interface controller. The circuit 142is generally operational to control the interface between the circuit120 and the circuits 144 and 158. Controls may include, but are notlimited to, commands to start and stop the device 154 and/or commands toposition the device 152. Information may include, but is not limited to,the position of the device 152.

The circuit 144 may implement a read/write channel circuit. In a writemode, the circuit 144 is generally operational to format write data in aform suitable for storage in the device 104. In a read mode, the circuit144 may be operational to reformat the data read from the device 104.

The circuit 146 may implement a preamplifier circuit. In the write mode,the circuit 146 is generally operational to amplify the write datareceived from the circuit 144. In the read mode, the circuit 146 isgenerally operational to amplify the read data received from the device104.

The circuit 148 may implement one or more read/write head assemblies.Each head assembly 148 generally resides at the end of an arm pivotablyattached to the device 152. Each write head of each head assembly 148 isgenerally operational in the write mode to store the write data receivedin the signal DATA in the device 150. In the read mode, each read headof each head assembly 148 is operational to read data from the device150.

The device 150 may implement one or more disk platters. Each platter 150is generally operational to store data in (on) a nonvolatile medium. Invarious embodiments, each platter 150 may have two sides in which thedata is stored. The data on the platter 150 generally comprises groupsof magnetic signals that may be detected by the head assembly 148 whenthe head assembly 148 is properly positioned relative to the platter150.

The device 152 may implement a voice coil motor (e.g., VCM) circuit. Thedevice 152 is generally operational to position the head assembly 148 ina radial direction along the surfaces of the platter 150. Thepositioning of the head assembly 148 by the device 152 may be controlledby the signal MT. The actual position and/or velocity of the headassembly 148 may be reported by the device 152 in the signal POS.

The device 154 may implement a spindle motor circuit. The device 154 isgenerally operational to rotate the platter 150 at a speed (e.g., 5,400to 10,000 revolutions per minute). Speed of the rotation may becontrolled by the signal SPEED.

The circuit 156 may implement a motor controller. The circuit 156 isgenerally operational to generate the signal CMD and the signal SPEED tocontrol the rotational speed of the platter 150 and the positioning ofthe head assembly 148 relative to the platter 150.

The circuit 158 may implement a hard disk controller. The circuit 158 isgenerally operational to control generation of the signals that governthe reading to and writing from the device 104. The circuit 158 maycontrol operations of the device 104 through the circuit 156. Thecircuit 158 may provide the position and/or velocity feedback to thecircuit 142.

In a typical read operation, the head assembly 148 may be accuratelyaligned by the circuit 156 and the device 152 to a desired data track onthe platter 150. The circuit 156 both positions the head assembly 148 inrelation to the platter 150 and drives the spindle motor device 154. Thedevice 154 may spin the platter 150 at a determined spin rate (e.g.,RPMs). The read channel circuit 144 may receive information from thecircuit 146 and perform a data decode/detection process to recover thedata (e.g., the signal READ DATA) stored by the platter 150.

In operation, the head assembly 148 may be positioned adjacent a datatrack on the platter 150. Magnetic signals representing data on theplatter 150 may be sensed by the head assembly 148 as the platter 150 isrotated by device 154. The sensed magnetic signals may be provided as acontinuous, minute analog signal representative of the magnetic data onthe platter 150. The analog signal may be transferred from the headassembly 148 to the circuit 144 via the preamplifier circuit 146. Thecircuit 146 is generally operable to amplify the analog signals accessedfrom the platter 150. In turn, the read channel circuit 144 may decodeand digitize the received analog signal to recreate the informationoriginally written to the platter 150. The data is provided as read datain the signal READ DATA.

In a typical write operation, the circuit 144 may receive write data(e.g., the signal WRITE DATA) and provide the write data to the circuit146 in a form writable to the platter 150. A write operation issubstantially the opposite of the read operation with write data in thesignal WRITE DATA being provided to the circuit 144. The write data maysubsequently be encoded and written to the platter 150. In someembodiments, the circuit 144 is implemented as a separate integratedcircuit.

In the logical block addressing scheme, sectors may be numbered asinteger indexes. When mapped to CHS (cylinder-head-sector) tuples, thelogical block address numbering generally starts with an initialcylinder, an initial head, and an initial sector in an initial track.Once the track is exhausted, numbering may continue to a next head,while staying in the initial cylinder. Once all of the sectors insidethe initial cylinder are exhausted, the numbering generally continues tothe next cylinder, and so on. Thus, the lower the logical block addressvalue is, the closer the physical sector is to an outermost cylinder ofthe hard drive.

The CHS values may be mapped to the logical block addresses per formula1 as follows:LBA=(C×HPC+H)×SPT+(S−1),   (1)where C, H and S may be the cylinder number, the head number, and thesector number, respectivly, LBA may be the logical block address, HPCmay be a maximum number of heads per cylinder (usually reported by thedisk drive, typically 16 for a 28-bit LBA) and SPT may be a maximumnumber of sectors per track (usually reported by the disk drive,typically 63 for the 28-bit LBA).

The logical block addresses may be mapped to the CHS values per formulae2-4 as follows:C=LBA÷(HPC×SPT),   (2)H=(LBA÷SPT) mod HPC,   (3)S=(LBA mod SPT)+1,   (4)where the operation “mod” may be a modulo operation.

Consider an example translation where S may range from 1 to 63, H mayrange from 0 to 15 and C may range from 0 to 31. Since each platter hastwo sides, a total number of platters may be 8 and hence a total numberof heads is 16. Example translations of several logical block addressvalues into corresponding CHS values may be illustrated in Table I asfollows:

TABLE I LBA value C, H, S Values 0 0, 0, 1 1 0, 0, 2 2 0, 0, 3 62 0, 0,63 945 0, 15, 1 1007 0, 15, 63 1008 1, 0, 1 1070 1, 0, 63 1071 1, 1, 11133 1, 1, 63 1134 1, 2, 1 2015 1, 15, 63 2016 2, 0, 1 16,127 15, 15, 6316,128 16, 0, 1 32,255 31, 15, 63Other numbers of cylinders, heads and sectors may be implemented to meetthe criteria of a particular application.

Some common hard disk drives use a zone-bit recording (e.g., ZBR)arrangement. Without the zone-bit recording, an inner zone of theplatter 150 generally has a higher bit density than an outer zone of theplatter 150. With zone-bit recording, as a distance from the center ofthe platter 150 increases, the number of sectors in a given angleincreases. Various embodiments of the circuit 100 may be implemented towork with platters 150 that do not implement the zone-bit recording.Other embodiments of the circuit 100 may be implemented to work withplatters 150 that implement the zone-bit recording.

Consider the following example where the platter does not implement thezone-bit recording. Since all of the heads of the head assembly 148generally move together, a structure of the physical address may begiven by Table II as follows:

TABLE II C0 H0 H1 . . . . . . . . . . . . . . . . . . H15 S1 S1 S1 S2 S2S2 . . . . . . . . . S63 S63 S63 C1 H0 H1 H15 S1 S1 S1 S2 S2 S2 . . . .. . . . . S63 S63 S63 C2 H0 H1 H15 S1 S1 S1 S2 S2 S2 . . . . . . . . .S63 S63 S63 . . . . . . . . . . . . C31 H0 H1 H15 S1 S1 S1 S2 S2 S2 . .. . . . . . . S63 S63 S63A similar mechanism may be used with the zone-bit recording by changingparameters in the calculations used to find the physical sectoraddresses. For example, the table may be adjusted to include moresectors in the outer cylinders of the platters 150.

Referring to FIG. 3, a functional flow diagram of a sector translationlayer is shown. The circuit 122 may store multiple maps (or tables) 160and 162. The circuit 120 generally comprises a block (or circuit) 164.The circuit 164 may buffer maps (or tables) 166 and 168.

The circuit 164 may implement a cache circuit. The circuit 164 isgenerally operational to buffer all or a portion of each map stored inthe circuit 122. In various embodiments, the circuit 164 is designed aspart of the circuit 120. In other embodiments, the circuit 164 may beseparate from the circuit 120.

In some embodiments, the circuit 164 may be designed as a random accessmemory (e.g., RAM). The RAM may have a low-access latency. The RAM maybe controlled to function as a cache for the maps. In variousembodiments, a common double data rate (e.g., DDR) RAM may be used toimplement the circuit 164. For example, a 4,096 byte sector size with a2 terabyte capacity in the device 104 generally results in 64 megabytesof data in the map 168.

The map 160 may implement a logical address (e.g., LA) to physicaladdress (e.g., PA) translation map (or table). Entries of the map 160generally identify physical addresses of sectors in the device 104 thatcorrespond to logical block addresses generated by the circuit 92. Invarious embodiments, the map 160 may be implemented as a multi-level(e.g., two level) address translation layer.

The map 162 may implement a physical address free sector (e.g., PA-FREESECTOR) bitmap. The map 162 generally maintains a flag for each sectorin the device 104. In various embodiments, each flag may be a singlebit. Each flag in a free state (e.g., a logical one state) generallyindicates that the corresponding sector in the device 104 currentlycontains stale data or no data (e.g., unwritten) and so is free to bewritten. Each flag in an occupied state (e.g., a logical zero state)generally indicates that the corresponding sector in the device 104currently contains valid data (e.g., written).

The map 166 may be a cached copy containing all or a portion of the map160. In various embodiments where the map 160 is a two-level sectortranslation map, the map 166 may comprise the first level and portionsof the second level of the map 160. Other combinations of map levels maybe implemented to meet the criteria of a particular application.

The map 168 may be a cached copy containing all or a portion of the map162. In some embodiments, the map 168 may be cached copy of the entiremap 162. In other embodiments, the map 168 may contain a portion of themap 162 corresponding to the tracks (or cylinders) neighboring a currentposition of the head assembly 148. For example, the map 168 may includeflags of the current track aligned to the head assembly 148 and flagsfor N (e.g., 3 to 5) tracks to either side of the current track.

Therefore, the map 168 may be used to quickly identify free (stale dataor unwritten) sectors near the head assembly 148. Hence, writes may bequickly committed to the media with little to no movement of the headassembly 148. The number of neighboring tracks generally depends on thespeed at which the head assembly 148 may change tracks relative to thespeed at which the flags of a new track may be copied from the map 162to the map 166.

In various embodiments, the full first level of the map 160 and the fullmap 162 may be copied to the maps 166 and 168 on power up. Movement ofthe head assembly 148 among the tracks may result in flushing out of thecache contents to the circuit 122. Existing cache content may be writtenout before loading the next content from the circuit 122 to the cache164 if the existing cache content is dirty. If the cache 164 is notdirty, no writes to the circuit 122 may happen. In situation where thecache 164 is loaded only for reading, no cache flushing may beperformed.

The cache flushing may be triggered on a power loss. Power losscircuitry may initiate the flushing of the cache 164 to the circuit 122.An onboard capacitor generally maintains enough charge to support theflushing of pending maps and checkpoints in the cache 164 to the circuit122. The cache flushing may also be triggered by the circuit 92. Forexample, a standby immediate command (e.g., a command to move a deviceinto a standby mode) may cause the circuit 120 to flush the contents ofthe cache 164 to the circuit 122. The cache flushing may also betriggered at checkpoint intervals. For example, the maps 166 and 168 maybe flushed to the maps 160 and 162 every few (e.g., 2) seconds.

In some embodiments, the map 162 may be stored in a NOR flash memory.The NOR flash generally permits the map 162 to be accessed like a randomaccess memory as the head assembly 148 moves across the platter 150.Therefore, the cached map 168 may be eliminated.

Referring to FIG. 4, a diagram of an example portion of the platter 150is shown. The platter 150 is shown having multiple tracks (or cylinders)170 a-170 d. The head assembly 148 may be currently aligned to engage acurrent track (e.g., 170c as shown).

The circuit 92 may issue a write command with a logical block addressand a count value to the circuit 100 at any time. The circuit 102 (e.g.,the circuit 120) may respond to the write command by identifying aphysical address in the LA-to-PA map 166 that corresponds to the logicalblock address. If the physical address is in the current track (e.g.,170 c) and approaching the head assembly 148, the circuit 120 may waitfor the platter 150 to rotate and then write the data into theappropriate physical address. If the physical address is not in thecurrent track (e.g., 170 c), the circuit 120 may search the map 168 tolocate information about one or more next free sector near where thehead assembly 148 is currently placed. The circuit 120 may allocate theidentified free sectors for the write and update the map 168 to indicatethat the free sectors are written. The map 166 may also be updated tolink the logical block address to the about-to-be-written free sectors.After the data has been written in the medium, the map 166 and/or themap 168 may be flushed to the circuit 122 based on a caching policy ofthe circuit 100. Updating between the maps 160 and 166 and between maps162 and 168 may be programmable. The programming may be provided by thecircuit 92 and/or during manufacturing.

Some embodiments of the circuit 100 may include one or more policiesregarding writes to free sectors. Consider a case where each sector hasa size of several (e.g., 4) kilobytes. Under a particular write policy(e.g., a write policy A), an initial write command may be received bythe circuit 100 with a logical block address of 300 and a count value of8 sectors. The circuit 120 may inspect the map 168 and find that acurrent sector at a physical address of zero is about to reach the headassembly 148.

Therefore, the free sector map 168 may be updated by the circuit 120 toindicate that the physical addresses of the sectors 0 to 7 are written.The circuit 120 may map (or link) the logical block address of 300 tothe current physical address (e.g., 0) with a length of 8. The circuit120 may optionally flush one or both of the maps 166 and/or 168 to thecircuit 122.

Continuing the example, the circuit 92 may issue another write commandfor a logical block address of 700 with a count value of 4 sectors. Thecircuit 120 generally responds to the write command by checking the map168 for free sectors. Since the head assembly 148 is still in thecurrent track, the circuit 120 may allocate the free sectors at physicaladdresses 8 to 11 as written in the map 168. The map 166 may be updatedto link the logical block address of 700 to the physical address of 8with a length of 4. One or both maps 166 and/or 168 may subsequently beflushed to the circuit 122. The write data associated with the currentwrite command may be written to the platter 150 in the sectors with thephysical addresses of 8 to 11.

The circuit 92 may issue a third write command with a logical blockaddress of 304 and a count value of 8 sectors. The circuit 120 generallyresponds to the write command by checking the map 168 for free sectors.Since the head assembly 148 is still in the current track, the circuit120 may allocate the free sectors at physical addresses 12 to 19 aswritten in the map 168. The map 166 may be updated to link the logicalblock address of 304 to the physical address of 12 with a length of 8.The write data associated with the current write command may be writtento the platter 150 in the sectors with the physical addresses of 12 to19. Note that the logical block addresses 304 to 307 were previouslywritten by the initial write command (e.g., LBA 300 with a sector countof 8) into physical addresses 4 to 7. Therefore, the circuit 120 mayupdate the free sector map 168 to show that the sectors at the physicaladdresses 4 to 7 are now free (contain stale data). One or both maps 166and/or 168 may subsequently be flushed to the circuit 122.

In some write policies (e.g., a write policy B), the circuit 120 mayseek the nearest track containing a sequence of contiguous free sectorssufficiently large to store all of the data associated with the writecommand. Consider a case as shown in FIG. 4 where the head assembly 148is about to reach multiple (e.g., 4) free sectors 172. If the writecommand has too much data for the free sectors 172 to store, the circuit120 may conclude that the free sectors 178 are the nearest set ofcontiguous free sectors. Therefore, the head assembly 148 may be movedfrom the current track 170 c to the track 170 a to align with the freesectors 178. Depending on the speed of the voice coil motor 152 and thespindle motor 154, the head assembly 148 may reach the free sectors 178in the track 170 a in less than a single rotation of the platter 150 orafter one or more rotations of the platter 150.

In other write policies, the circuit 120 may split writes into multiplesegments of sequential free sectors. Consider again the case as shown inFIG. 4 where the head assembly 148 is about to reach the four sequentialfree sectors 172. A write command may be received with a sector countvalue of greater than four (e.g., count value=6). The circuit 120 maysearch the map 168 for free sectors near the current position of thehead assembly 148 and conclude that the initial four sectors 172 may bewritten with the data associated the initial four logical blockaddresses. The circuit 120 may decide to write the remaining two sectorsof data in the free sectors 176 (e.g., a write policy C to usetemporally nearest free sectors) or in the free sectors 174 (e.g., awrite policy D to use the physically nearest free sectors). Selection ofthe free sectors generally depends on the speed of the voice coil motor152 and the speed of the spindle motor 154. In another write policy(e.g., a write policy E), the circuit 120 may conclude that the nearestfree sectors are any free sectors within the current track. Anotherwrite policy (e.g., a write policy F) generally splits the write datainto two or more parts and writes each part substantially simultaneouslyon a different surface of one or more platters 150. Other write policiesmay be implemented to meet the criteria of a particular application.

Referring to FIG. 5, a functional flow diagram of an example technique180 for mapping the logical block addresses to the physical addresses isshown. The technique (or method or process) 180 may be performed by thecircuits 120 and 164. The technique 180 generally comprises a step (orstate) 182, a step (or state) 184, a step (or state) 186, a step (orstate) 188, multiple steps (or states) 190 a-190 n and multiple steps(or states) 192 a-192 n. The steps 180 to 192 n represent modules and/orblocks, embodiments of which include one or more of hardware circuitry,executable code (e.g., software, microcode, programming instructions,firmware, etc.) in a storage device used by the hardware circuitry, oneor more electronic design tools, and/or other implementations.

Second-level map parameters maybe stored in programmable registers ofthe circuit 120 in the step 182. The circuit 92 may provide an accesscommand (e.g., a read command or a write command) with a logical blockaddress to the circuit 120. An integer division of the logical blockaddress may be performed by the circuit 120 in the step 184 based on theparameters stored in the registers in the step 182. A quotient of thedivision generally establishes a first-level map index value (e.g., FLMINDEX). A remainder of the division forms a second-level map page index(e.g., SLM PAGE INDEX). In some embodiments, the divider step 184 may becoupled to the first-level map 186 and the one or more second-level mappages 188 (a representative single second level page is shown). Invarious embodiments, some or all of the process of mapping logical blockaddresses, such as the divider step 184, is implemented (e.g., infirmware or software) executing in the circuit 120.

A mapping of the logical block addresses to the physical addresses ofthe sectors in the device 104 may be a two-level map having afirst-level map 186 and one or more second-level map pages 188. Thetwo-level map may be implemented via first-level map elements coupled toone or more second-level map elements. The first-level map 186 generallyincludes a plurality of entries (or pages) 190 a-190 n. Each entry 190a-190 n may contain information about a corresponding second-level mappage. Each entry 190 a-190 n of the first-level map 186 may point to arespective one of the second-level map pages (such as the second-levelmap page 188).

Each second-level map page 188 may include a plurality of entries 192a-192 n. Each entry 192 a-192 n generally contains information about aphysical address of a corresponding sector.

Each entry 192 a-192 n may point to a location in the device 104 wheredata begins (e.g., a read unit storing at least the beginning of hostwrite data for a logical block address).

The quotient FLM INDEX may be used to select a first-level map entry 190a-190 n. A page field of the selected first-level map entry may be readas a second-level map pointer (e.g., SLM POINTER). The page field isused to select a second-level map 188, and the remainder SLM PAGE INDEXmay be used (e.g., as an offset) to select an entry 192 a-192 n of theselected second-level map page 188.

A field of the selected second-level map page entry 192 a-192 n may beused to select a particular physical address (e.g., PA) location in thedevice 104 where at least a beginning of the sector sequencecorresponding to the presented logical block address is stored. Invarious embodiments, the physical addresses include cylinder values,head values and sector values.

In various embodiments, the quotient may be used as a key to access thecache (e.g., the circuit 164), such as a fully associative cache of thesecond-level map pages. If a hit occurs in the cache for a particularsecond-level map page, a latest copy of the particular second-level mappage may be found in the cache without accessing the map 160 in thecircuit 122. Providing fast access to a plurality of second-level mappages enables, in some embodiments and/or usage scenarios, may result inmore efficient processing of multiple independent streams of sequentialdata accesses to the device 104 (e.g., a stream of sequential dataaccesses to a region of logical block addresses interspersed withanother stream of sequential data accesses to another region of logicalblock addresses).

Referring to FIG. 6, a flow diagram of an example implementation of awrite method 200 is shown. The method (or process or operation) 200 maybe implemented by the circuits 104 and 120-124. The method 200 generallycomprises a step (or state) 202, a step (or state) 204, a step (orstate) 206, a decision step (or state) 208, a step (or state) 210, astep (or state) 212, a step (or state) 214, a step (or state) 216, astep (or state) 218, a decision step (or state) 220 and a step (orstate) 222. The steps 202-222 may represent modules and/or blocks,embodiments of which include one or more of hardware circuitry,executable code (e.g., software, microcode, programming instructions,firmware, etc.) in a storage device used by the hardware circuitry, oneor more electronic design tools, and/or other implementations. Thesequence of the steps is shown as a representative example. Other steporders may be implemented to meet the criteria of a particularapplication.

In the step 202, the circuit 120 may receive from the circuit 92 a writecommand with a logical address. In parallel (or sequentially orconcurrently), the circuit 120 may lookup free sectors near the heads inthe step 204 and begin fetching a second level map (e.g., SLM) for thelogical address in the step 206, if not already cached. In the decisionstep 208, the circuit 120 may determine if the nearest free sectors (pera current one or more write policies) is in the same cylinder as thehead assembly 148. If the nearest free sectors are in a differentcylinder, the circuits 120 and 124 may command movement of the headassembly 148 in the step 210. In the step 212, the circuit 120 may waitfor the selected free sectors to reach the selected head assembly 148.

The circuits 120 and 124 and the head assembly 148 may write the writedata into the free sectors in the step 214. The free sector map 168 maybe updated by the circuit 120 in the step 216. If the just-written datais an updated version of previously written data currently stored in thedevice 104, flags of the sectors holding the now-obsolete data may bemarked as free. Flags of the newly-written sectors may be marked aswritten.

The circuit 120 may update the translation map 166 in the step 218. Theupdate may include changing the logical address to physical addressmapping and marking the updated second level maps as dirty. A check maybe performed by the circuit 120 in the step 220 to determine if thesector count of the write command is done. If more data remains to bewritten, the method 200 may return to the step 204 and 206 to findadditional free sectors. Once all the data has been written, thecircuits 120 and 124 may command movement of the head assembly 148 to adefragmented and/or free cylinder in the step 222.

Referring to FIG. 7, a flow diagram of an example implementation of atrim method 240 is shown. The method (or process or operation) 240 maybe implemented by the circuits 104 and 120-124. The trim method 240 maybe performed without accessing the device 104 or altering any datastored in (on) the device 104. The method 240 generally comprises a step(or state) 242, a step (or state) 244, a step (or state) 246, a step (orstate) 248 and a decision step (or state) 250. The steps 242-250 mayrepresent modules and/or blocks, embodiments of which include one ormore of hardware circuitry, executable code (e.g., software, microcode,programming instructions, firmware, etc.) in a storage device used bythe hardware circuitry, one or more electronic design tools, and/orother implementations. The sequence of the steps is shown as arepresentative example. Other step orders may be implemented to meet thecriteria of a particular application.

In the step 242, the circuit 120 may receive a trim command from thecircuit 92. The trim command generally includes a logical block addressand sector count value of data stored in the device 104 that is nolonger used by the circuit 92. The circuit 120 may begin fetching asecond level map for the logical address in the step 244, if not alreadycached. In the step 246, the circuit 120 generally updates the secondlevel map information in the translation map 166 in response to the trimcommand. The update may include setting the physical address to a trimvalue (e.g., a predetermined out of range value) and marking the secondlevel map as dirty in the map 166. The circuit 120 may also update thefree sector map 168 in the step 248 in response to the trim command. Theupdate may mark as free the old (former) physical addresses of thetrimmed sectors. A check may be performed by the circuit 120 in the step250 to determine if all of the trimmed sectors have been processed. Ifnot, the method 240 may return to the step 244 and fetch another secondlevel map that corresponds to the unprocessed sectors. Once all of thetrimmed sectors have been processed, the method 240 may end.

Referring to FIG. 8, a flow diagram of an example implementation of adefragmentation method 260 is shown. The method (or process oroperation) 260 may be implemented by the circuits 104 and 120-124. Themethod 260 generally comprises a step (or state) 262, a step (or state)264, a step (or state) 266, a step (or state) 268, a step (or state)270, a step (or state) 272 and a step (or state) 274. The steps 262-274may represent modules and/or blocks, embodiments of which include one ormore of hardware circuitry, executable code (e.g., software, microcode,programming instructions, firmware, etc.) in a storage device used bythe hardware circuitry, one or more electronic design tools, and/orother implementations. The sequence of the steps is shown as arepresentative example. Other step orders may be implemented to meet thecriteria of a particular application.

In the step 262, a defragmentation may be triggered by the circuit 120.In various embodiments, the trigger may be an input/output rate from thecircuit 92 falling below a threshold and/or the circuit 100 having timeto run background tasks. The circuit 120 may locate valid data stored inthe sectors of every other cylinder (e.g., cylinders N, N+2, N+4, etc.)in the step 264. In various embodiments, the sectors containing thevalid data may be marked in the free sector map 168 as written. Thecircuit 120 may copy the valid data from some to all of the locatedsectors in the step 266 into a buffer. The buffered valid data may bewritten back to the circuit 104 in free sectors in every other(alternate) cylinder (e.g., cylinders N+1, N+3, N+5, etc.) in the step268. In the step 270, the free sector map 168 may be updated to flag thesectors containing the valid data copied into the cylinders N+1, N+3,N+5, etc. as written, and the sectors containing the data left behind inthe cylinders N, N+2, N+4, etc. as free. The circuit 120 may also updatethe translation map 166 in the step 272 such that the logical blockaddresses are translated into the new physical locations. In the step274, the circuits 120 and 124 may command movement of the head assembly148 into alignment with a cylinder now containing all free sectors(e.g., a defragmented/free cylinder). Creation of the defragmentedcylinders full of free sectors and locating the head assembly 148 on ornear such cylinders generally speeds up writes because the writes may bedone into the free sectors of the defragmented/free cylinders withlittle to no movement of the head assembly 148. Other defragmentationsequences of written cylinders and free cylinders may be implemented tomeet the criteria of a particular application.

In some embodiments, the circuit 100 may be overprovisioned. Anoverprovisioned circuit 100 generally has more available space on theplatter 150 than is known to the circuit 92. For example, the platter150 may provide several (e.g., 20-30) percent overprovisioning.Therefore, a track may be kept free every few tracks by the circuit 120(e.g., 1 track free in every 4 tracks for a 25% overprovisioning). Afterdefragmentation of the platter 150, the tracks N, N+1, N+2 and N+3 maycontain the valid data while the track N+4 may be completely empty.

Referring to FIG. 9, a flow diagram of an example implementation of acache flush method 280 is shown. The method (or process or operation)280 may be implemented by the circuits 120, 122 and 164. The cache 164generally contains a group 282 of nodes 284 a-284 n. The nodes 284 a-284n may be sorted within the group 282 into dirty nodes and non-dirty (orclean) nodes. A current level of the group 282 generally separates thedirty nodes from the non-dirty nodes. The method 280 generally comprisesa decision step (or state) 290, a step (or state) 292, a step (or state)294 and a step (or state) 296. The steps 290-296 may represent modulesand/or blocks, embodiments of which include one or more of hardwarecircuitry, executable code (e.g., software, microcode, programminginstructions, firmware, etc.) in a storage device used by the hardwarecircuitry, one or more electronic design tools, and/or otherimplementations. The sequence of the steps is shown as a representativeexample. Other step orders may be implemented to meet the criteria of aparticular application.

In the decision step 290, the circuit 120 may check the current level ofthe node group 282. If the current level is below a second level mapflush watermark level (e.g., not many dirty nodes), the method 280 mayend. If the current level is higher than the second level map flushwatermark level (e.g., too many dirty nodes), a copying of the map 166to the circuit 122 (e.g., a flush of the map 166 to the map 160) may beperformed in the step 292. In the step 294, the just-flushed dirty nodesin the node group 280 may me marked as clean. In the step 296, the firstlevel map may be updated with the flash addresses of the second levelmaps.

Various embodiments may include one or more policies for handling readcommands. Consider again the case where each sector has a size ofseveral (e.g., 4) kilobytes. An initial read policy (e.g., read policyA) may handle a single read command at a time.

For example, the circuit 120 may receive a read command with the LEA of300 with the sector count value of 8. The translation map 166 maytranslate the LEA of 300 to the physical address of zero and a length of4 (because the sectors 4-7 were marked as free sectors due to theexample third write command). The circuit 120 may translate the next LEA304 to the physical address of sector 12 with a length of 8. Thephysical sectors 0-3 and 12-15 may be read in order or in a rearrangedorder to optimize the head movement.

Referring to FIG. 10, a flow diagram of an example implementation of asingle read method 300 is shown. The method (or process or operation)300 may be implemented by the device 104 and the circuits 120-124. Themethod 300 generally comprises a step (or state) 302, a step (or state)304, a decision step (or state) 306, a step (or state) 308, a step (orstate) 310, a step (or state) 312, a decision step (or state) 314 and astep (or state) 316. The steps 302-316 may represent modules and/orblocks, embodiments of which include one or more of hardware circuitry,executable code (e.g., software, microcode, programming instructions,firmware, etc.) in a storage device used by the hardware circuitry, oneor more electronic design tools, and/or other implementations. Thesequence of the steps is shown as a representative example. Other steporders may be implemented to meet the criteria of a particularapplication.

In the step 302, the circuit 120 may receive from the circuit 92 a readcommand with a logical address. The circuit 120 generally translates thelogical block address into a physical address in the step 304. A checkis made in the step 304 by the circuit 120 to determine if the databeing accessed is currently trimmed (e.g., check the physical addressfor the predetermined out of range value). If the data is currentlytrimmed, the circuit 120 may return all zeros to the circuit 92 in thestep 310.

If the requested data is currently valid (e.g., is not currentlytrimmed), the circuit 120 may command the circuit 124 to move the arm toposition the head assembly 148 in the appropriate cylinder in the step308. Once the head assembly 148 is positioned, the requested read datamay be read from the platter 150 in the step 312 by the circuit 124.

A check may be performed by the circuit 120 in the step 314 to determineif all of the requested read data has been obtained from the platter150. If not, the method 300 may return to the step 304 to determine thenext physical address to be read. Once the read request has beenserviced, the circuits 120 and 124 may command movement of the headassembly 148 to a defragmented/free cylinder in the step 316 inpreparation for a write command.

Referring to FIG. 11, a flow diagram of an example implementation of amultiple read method 320 is shown. The method (or process or operation)320 may be implemented by the device 104 and the circuits 120-124. Themethod 320 generally comprises a step (or state) 322, a step (or state)324, a step (or state) 326, a step (or state) 328, a step (or state)330, a step (or state) 332, a step (or state) 334, a decision step (orstate) 336 and a step (or state) 338. The steps 322-338 may representmodules and/or blocks, embodiments of which include one or more ofhardware circuitry, executable code (e.g., software, microcode,programming instructions, firmware, etc.) in a storage device used bythe hardware circuitry, one or more electronic design tools, and/orother implementations. The sequence of the steps is shown as arepresentative example. Other step orders may be implemented to meet thecriteria of a particular application.

In the step 322, the circuit 120 may receive from the circuit 92 a rapidsequence of multiple read commands. In the step 324, the circuit 120 maybuffer the read commands. The circuit 120 may subsequently rearrange thesequence of read commands in the step 326 to improve movement efficiencyof the head assembly 148 during the read sequence.

In the step 328, the circuits 120 and 124 may command movement of thehead assembly 148 to a cylinder corresponding to an initial read commandin the rearranged sequence of read commands. An initial read of the readdata may be performed by the circuits 120 and 124 in the step 330. Inthe step 332, the circuits 120 and 124 may command movement of the headassembly 148 to a next read command in the rearranged sequence. Thecircuits 120 and 124 may read the next read data from the media in thestep 334.

If one or more read commands remain to be serviced, the decision step336 may return to the step 332. Thereafter, the head assembly 148 may bemoved again and the next read data may be read from the media. The looparound the step 332, 334 and 336 may continue until all of the readcommands in the rearranged list of read commands have been serviced. Inthe step 338, the circuit 120 and 124 may command movement of the headassembly 148 to a defragmented/free cylinder in the step 338 to preparefor a new write command.

Referring to FIG. 12, diagrams illustrating head movement based on aread sequence with and without rearrangement are shown. In an examplemovement without rearrangement 360, a temporal sequence of three readcommands 362 (e.g., LBA 1000), 364 (e.g., LBA 1001) and 366 (e.g., LBA1002) is shown. To service the read command 362, the head assembly 148is moved from a current location to an outer track to access the LBA1000. After the read command 362 has been completed, the head assembly148 is moved 390 to an inner track to service the read command 364 toaccess the LBA 1001. After the read command 364 has completed, the headassembly 148 is moved again 392 to a middle track to service the readcommand 366.

In the example movement with the rearrangement 370, the rearrangedsequence of read commands may be 364, 366 and 362. The head assembly 148may be initially moved to the inner track to service the read command364 to access the LBA 1001. After the read command 364 has completed,the head assembly 148 may be moved 392 to the middle track to servicethe read request 366. After the read command 366 has completed, the headassembly 148 may be moved again 394 to the outer track to service theread request 362. By rearranging the read commands, the head assembly148 movement may be along an overall shorter path because the movement394 in the rearranged sequence is shorter than the movement 390 in theoriginal sequence. Thus, the rearranged read commands may be serviced inless time than in the original sequence of commands.

Referring to FIG. 13, a block diagram of an example implementation of anapparatus 90 a is shown. The apparatus 90 a may be a variation on theapparatus 90. The apparatus 90 a generally comprises the circuit 92 anda block (or circuit) 100 a. The circuit 100 a generally comprises ablock (or circuit) 102 a and the device 104. The circuit 102 a generallycomprises the circuit 120, the circuit 122, the circuit 124, a block (orcircuit) 382, a block (or circuit) 384 and a block (or circuit) 386. Thecircuits 100 a to 386 may represent modules and/or blocks, embodimentsof which include one or more of hardware circuitry, executable code(e.g., software, microcode, programming instructions, firmware, etc.) ina storage device used by the hardware circuitry, one or more electronicdesign tools, and/or other implementations.

The signal MAPS may be exchanged between the circuit 122 and the circuit384. One or more signals (e.g., H) may be exchanged between the circuit120 and the circuit 386. The signal H generally carries commands anddata received from and sent to the host circuit 92. Components of thesignal H may include, but are not limited to, read commands, read data,write command, write data, trim commands and/or defragment commands. Oneor more signals NVM may be exchanged between the circuit 382 and thecircuit 384. Components of the signal NVM may convey nonvolatile memorycommands and map data. One or more signals (e.g., C) may be exchangedbetween the circuit 120 and the circuit 382. Components of the signal Cmay include, but are not limited to, the map data, cache flushingcommands and/or cache fetching commands.

The circuit 382 is shown as the cache circuit external to the circuit120. The circuit 164 may be in communication with the circuit 120 topermit the circuit 120 to access the maps 166 and 168. The circuit 382may also be in communication with the circuit 384 to flush the cachedata to the circuit 122 and fetch data from the circuit 122 to updatethe cache.

The circuit 384 may implement a nonvolatile memory interface circuit.The circuit 384 is generally operational to control the circuit 122,read data from the circuit 122 and write data to the circuit 122.Additional operations of the circuit 384 may include, but are notlimited to, error correction encode data written to the circuit 122,decode (e.g., hard decode and/or soft decode) and error correct dataread from the circuit 122, adjust read threshold voltages in the circuit122, perform wear leveling on blocks in the circuit 122, perform garbagecollection in the circuit 122, control read amplification in the circuit122, control read disturb in the circuit 122, and command block erasesin the circuit 122.

The circuit 386 may implement a host interface circuit. The circuit 386is generally operational to provide communication between the circuit120 and the circuit 92 via the signal HOST I/O.

Other signals may be implemented between the circuits 92 and 386 to meetthe criteria of a particular application.

Various embodiments of the present invention may aid in minimizing headseek during random writes thereby improving both writing latency andwriting throughput. Writing to the nearest free sectors generallyresults in higher writing speed. Writing to multiple platter surfaces inparallel may also improve writing speed. An endurance of a servo headassembly may be improved by reducing the average movement used inservicing write commands. The trim operations may be easily supportedand may result in little to no head assembly/voice coil motor movement.

Various embodiments of the invention may implement a sector translationlayer to optimize the seek time and rotational delay that, in turn,generally improve the throughput of the drive. The controller may use apersistent storage to map LBA-to-CHS (e.g., logical address-to-physicaladdress) address translations.

Flash memory may be used at the persistent storage for suchapplications. When a write request received from the host, a map of freesectors nearest to the current head position may be analyzed. The writedata is subsequently written to the nearest unmapped free sectors. Thewrite technique generally reduces head movement and so may reduce boththe seek time delay and the rotational latency delay.

Various embodiments of the invention may reorder read commands so thatthe head traversal may be optimized (e.g., moved in a single direction).A buffer management capability may be included in the hard disk drivecontroller to transfer the read data to correct offsets in a buffer. Theresulting overall read time may be reduced relative to reading theplatter in the same order that the read commands were received.

The functions and structures illustrated in the diagrams of FIGS. 1-13may be designed, implemented, modeled, emulated and/or simulated usingone or more of a conventional general purpose processor, digitalcomputer, microprocessor, microcontroller and/or similar computationalmachines, programmed according to the teachings of the presentspecification, as will be apparent to those skilled in the relevantart(s). Appropriate software, firmware, coding, routines, instructions,opcodes, microcode, and/or program modules may readily be prepared byskilled programmers based on the teachings of the present disclosure, aswill also be apparent to those skilled in the relevant art(s). Thesoftware is generally embodied in a medium or several media, for examplenon-transitory storage media, and may be executed by one or more of theprocessors sequentially or in parallel.

Embodiments of the present invention may also be implemented by thepreparation of ASICs (application specific integrated circuits), FPGAs(field programmable gate arrays), PLDs (programmable logic devices),CPLDs (complex programmable logic device), sea-of-gates, ASSPs(application specific standard products), one or more integratedcircuits, circuitry based on hardware description languages, flashmemory, nonvolatile memory, random access memory, read-only memory,magnetic disks, floppy disks, optical disks such as DVDs and DVD RAM,and magneto-optical disks, modifications of which will be readilyapparent to those skilled in the art(s). As used herein, the term“simultaneously” is meant to describe events that share some common timeperiod but the term is not meant to be limited to events that begin atthe same point in time, end at the same point in time, or have the sameduration.

While the invention has been particularly shown and described withreference to the preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade without departing from the scope of the invention.

The invention claimed is:
 1. An apparatus comprising: a memoryconfigured to store data, the memory comprising a write head and aplurality of sectors in a plurality of tracks; and a controllercomprising a cache and a solid-state memory, wherein the solid-statememory is configured to store a sector map and a translation map, thesector map has a plurality of flags, and the controller is configured toreceive a write command that has a logical block address, copy a portionless than all of the sector map from the solid-state memory to the cachebased on a current position of the write head and an angular speedcapability of a voice coil motor that moves the write head relative tohow fast the flags of one of the tracks can be copied from thesolid-state memory to the cache, select one or more of the sectors fromthe sector map in the cache that are marked as free and are temporallyproximate to the write head based on the angular speed capability of thevoice coil motor and a rotational speed of the memory, write new dataassociated with the write command in the one or more sectors selected,and update the sector map in the cache according to the sectors wherethe new data was written, wherein each flag in the sector mapcorresponds to a respective one of the sectors and indicates whether therespective one of the sectors contains valid data or is free.
 2. Theapparatus according to claim 1, wherein the sector map and thetranslation map form a sector translation layer of the memory, and thememory comprises one or more rotating media and two or more of the writeheads.
 3. The apparatus according to claim 1, wherein the controller isfurther configured to begin a fetch of a portion less than all of asecond level map of the translation map that corresponds to the logicalblock address of the write command from the solid-state memory to thecache in parallel to selecting the one or more sectors from the sectormap in the cache.
 4. The apparatus according to claim 1, wherein thesectors temporally proximate to the write head comprise the sectors in acurrent one of the tracks presently aligned with the write head and oneor more of the tracks neighboring the current track that the write headcan reach relative to how fast the flags can be copied from thesolid-state memory to the cache.
 5. The apparatus according to claim 1,wherein the controller is further configured to move the valid data by adefragmentation operation to consolidate free space and to serializedata to ease access.
 6. The apparatus according to claim 1, wherein thecontroller is further configured to deallocate from the translation mapone or more of the sectors that contain the valid data per the sectormap in response to a trim command, and mark the sectors deallocated fromthe translation map as free in the sector map, wherein data in thesectors identified by the trim command is unaltered by the trim command.7. The apparatus according to claim 1, wherein the controller is furtherconfigured to receive a plurality of read commands in a first order, andrearrange the read commands in a second order to allow a read head tomove in a single direction while fulfilling the read commands.
 8. Theapparatus according to claim 1, wherein the memory and the controllerform part of a hard disk drive.
 9. The apparatus according to claim 1,wherein the controller is further configure to update the translationmap in the cache to associate the logical block address of the writecommand with a physical address of the sectors where the new data waswritten.
 10. A method of maintaining a sector translation layer in ahard disk drive, comprising the steps of: receiving at the hard diskdrive a write command that has a logical block address, wherein the harddisk drive comprises a write head, a plurality of sectors in a pluralityof tracks of a memory, a sector map, a translation map, the sector maphas a plurality of flags, and each flag in the sector map corresponds toa respective one of the sectors and indicates whether the respective oneof the sectors contains valid data or is free; copying a portion lessthan all of the sector map from a solid-state memory to a cache based ona current position of the write head and an angular speed capability ofa voice coil motor that moves the write head relative to how fast theflags of one of the tracks can be copied from the solid-state memory tothe cache; selecting one or more of the sectors from the sector map inthe cache that are marked as free and are temporally proximate to thewrite head based on the angular speed capability of the voice coil motorand a rotational speed of the memory; writing new data associated withthe write command in the one or more sectors selected; and updating thesector map in the cache according to the sectors where the new data waswritten.
 11. The method according to claim 10, wherein the sector mapand the translation map form a sector translation layer of the memory,and the memory comprises one or more rotating media and two or more ofthe write heads.
 12. The method according to claim 10, furthercomprising the step of: begin fetching a portion less than all of asecond level map of the translation map that corresponds to the logicalblock address of the write command from the solid-state memory to thecache in parallel to the selecting of the one or more sectors from thesector map in the cache.
 13. The method according to claim 10, whereinthe sectors temporally proximate to the write head comprise the sectorsin a current one of the tracks presently aligned with the write head andone or more of the tracks neighboring the current track that the writehead can reach relative to how fast the flags can be copied from thesolid-state memory to the cache.
 14. The method according to claim 10,further comprising the step of: moving the valid data by adefragmentation operation to consolidate free space and to serializedata to ease access.
 15. The method according to claim 10, furthercomprising the steps of: deallocating from the translation map one ormore of the sectors that contain the valid data per the sector map inresponse to a trim command; and marking the sectors deallocated from thetranslation map as free in the sector map, wherein data in the sectorsidentified by the trim command is unaltered by the trim command.
 16. Themethod according to claim 10, further comprising the steps of: receivinga plurality of read commands in a first order; and rearranging the readcommands in a second order to allow a read head to move in a singledirection while fulfilling the read commands.
 17. The method accordingto claim 10, further comprising the step of: updating the translationmap in the cache to associate the logical block address of the writecommand with a physical address of the sectors where the new data waswritten.
 18. The method according to claim 10, wherein the step areperformed in a hard disk drive.
 19. An apparatus comprising: aninterface circuit configured to process a plurality of read/writeoperations to/from a memory, wherein the memory comprises a write headand a plurality of sectors in a plurality of tracks; and a controlcircuit comprising a cache and a solid-state memory, wherein thesolid-state memory is configured to store a sector map and a translationmap, the sector map has a plurality of flags, and the control circuit isconfigured to receive a write command that has a logical block address,copy a portion less than all of the sector map from the solid-statememory to the cache based on a current position of the write head and anangular speed capability of a voice coil motor that moves the write headrelative to how fast the flags of one of the tracks can be copied fromthe solid-state memory to the cache, select one or more of the sectorsfrom the sector map in the cache that are marked as free and aretemporally proximate to the write head based on the angular speedcapability of the voice coil motor and a rotational speed of the memory,write new data associated with the write command in the one or moresectors selected, and update the sector map in the cache according tothe sectors where the new data was written, wherein each flag in thesector map corresponds to a respective one of the sectors and indicateswhether the respective one of the sectors contains valid data or isfree.
 20. The apparatus according to claim 19, wherein the interfacecircuit and the control circuit form part of a hard disk drive.